The Demon Holds the Keys to my Heart
by lemonofweirdness
Summary: SPOILERS! only if you have finished COLS! Sebastian is lonely. So when he stumbles across a young homeless girl, his life changes for the better. but when information arises about her family and past, Sebastian wonders, is this his destiny, to be with this girl, or death and destruction? FLUFF!
1. Prologue

Sebastian wouldn't admit it, but for the past few days he was lonely.

Of course, he had Jace, but he needed someone else. Not under his control, someone who could bring him back to life. Clary would be his first choice, but he couldn't wait for Clary. He needed someone soon, otherwise he would go mad.

He needed someone who could look after him.

Someone who could make him smile. Make him laugh.

Someone who could love him, and he could love back.

Someone like that.

Someone like me….


	2. Chapter 1-Homeless

"Elo! You got anything to spare! Food or money maybe?" Ben gave me his puppy-dog eyes, but it was hard. We had been through so much recently especially about Michael.

"Does it look like I am rich? Errr no!" I shouted back, hitting him lightly on the head with my damp, dirty sweater. Ben gave it to me as a present from Primark years ago, but it still fit because I was so thin. Being on the streets made you thin, but strong in case you had to defend yourself. It was likely, and Ben had already been scarred by that, so we always snuck in the gym on Sundays, just on the event of defending yourself. It had never actually helped but you never know!

"But El… we share! Remember? You get money off the violin, I work in the 'trade'"

I snorted knowing the 'trade' was pickpocketing. I and Ben hated it, but we had to band together to get money. We had to do whatever to survive.

I on the other hand, had a violin that had been passed down generations of my so called family. I never classed them as my family. My only family was Ben and Michael, and he was gone. I had to play the violin to get measly pennies to help get us by, money, food, clothes. The only comfort was that I was not alone. Others like me had no one.

I started taking my violin out of the case. It was very old had a name scrawled along the bottom

_Jem Carstairs_

But this Jem person was odd. The violin had a false bottom where knifes could be stored, and tubes, both large and small could be placed. Obviously this person was a psychopath.

I rubbed my charm bracelet for good luck. Michael got it for me on an unusual day, to say the least, and I have never took it off since. It is a glassy material, but it is not glass. It is so strange! But what is weirder were the charms. They were all symbols, like and eye, a diamond with flicks at the top, and so on.

I started singing whilst playing my violin. The song came to me in a dream, and it just worked.

I quickly looked up and say a boy with platinum blonde hair walking towards me.


	3. Chapter 2-Double Take

**Sebastian **

I had work to do today. I needed to know where the adamas, was. A new cup that could bring forth a new race of shadowhunters. But first I actually needed the cup first, otherwise the plan would never go ahead. At least I had an iron sister to carve it, but I needed the material.

So that's how I found myself stuck in York city centre, filled with tourists. I heard a local downworlder club had an idea of where it was, so that's where I was heading. After all, if they don't tell me, I may have to 'extract' the truth out of them. No one will miss downworlders, except their own kind. After all, the lives of a few downworlders are nothing compared to the power of these new shadowhunters. Better shadowhunters.

I started walking down a narrow winding road called the shambles. I had a glamour on, so the pathetic mundies wouldn't notice the glowing seraph blades shoved in my belt, the knifes in the top of my boots. They would scream and run. Anyway, it is more fun being invisible, as you get away with anything, and can eavesdrop. Of course, not all people are oblivious to glamour's, mundanes with the sight, downworlders, and the odd Nephilim. Of course any shadowhunters with the clave I met would be chopped up, blood running like a river in the pavement. I hope I didn't have to, I don't want to get dirty, and this is my only set of gear. Jace calls me a fussy girl.

So as I started to walk down this street. I heard it. An old song. A language mash up of English, German and Latin. But the words were oddly haunting, like something a shadowhunter would write in their spare time. With the violin, it was the most beautiful sound I had ever heard.

I quickly did a double take at the girl who was singing. Her voice was amazing but she looked so out of place in this well off area. She had and old sweater on, with too small jeans and a patchwork blanket protecting her from the chill that had started to set in. she was crammed in the alley just off the street, so people wouldn't trip over her, but still give money.

She must have been pretty at one point, but life on the streets must have aged her too quickly. She must have been 16 or 17 with greasy blonde hair, bordering on brown. She looked so thin and desperate, on breaking point. But she must be as hard as nails to live this life. She was muscly but not overly so, but curvy.

But 2 things struck me most of all. Her eyes, and her bracelet.

Her eyes were a warm brown. But when I got closer, I could see that they were not brown at all, but more like make of flecks of gold, dark and light. They may have seen so much, but they still had a twinkle in them. But that was rapidly fading. Soon that light would go out, and she would be empty.

I was reminded of someone but, who?

Her bracelet was very fine, with small crams over it. But it was definitely a shadowhunter bracelet, carved out of adamas and with charms of runes all over it. It was odd, because she had no weapons or marks on her. This added up to one thing:

This girl was a shadowhunter weather she knew it or not.

It's time we had a chat….


	4. Chapter 3-Sleep, Sight and Song

**Elo**

_The Herons start flying_

_When the day is dying,_

_But I am waiting for you_

_My Morgernstern_

_Who cares?_

_Who loves?_

_Who protects?_

_My Morgenstern_

_Where is your sight now?_

_As black as your tattoo's_

_As black as your runes_

_As black as your cor_

_i exspecto,_

_My Morgenstern…_

I slowly finished when I heard clapping from just above my head. I slowly looked up to see the blonde haired boy. I thought he had gone with a school group or something, as he was not from around these parts. But no, here he was in the flesh. His black eyes sapped the colour from his face, which made him even paler than he was. His angular face was looking straight at me and his mouth was tilted into a smile, but it looked forced. He looked hard to read.

In other words he was damn hot.

He held out a rough hand, the long fingers holding a strip of paper. When I looked closely it was not just a strip of paper, it was a £20. I was shocked. No-one had gave me this much money in my life.

I smiled truly, for one of the first times in my life.

"Thanks!"

He smiled and said

"Will you come with me? Please?"

I was immediately on my guard. My best mate Lily, disappeared. They said something similar happened to her. Thank god the violin case had a false bottom so I could hide a variety of knifes and crow bars in. at the moment I had a long cooking knife, and a short one in my shoe. Jem Carstairs may be a psycho, but thank god for the false bottom. I grabbed my stuff and put it in my small backpack and grabbed my violin case. No way on hell or earth was I leaving it here. It would be robbed in the blink of an eye.

"Ok!" best play along

He led me into a small back alley, but when I turned around, it was a dead end. I have walked these streets for YEARS and this has never been bricked up.

"Now, who are you?" his tone took a serious approach, not what I expected from a 17 year old guy who was flirting with me.

"For these purposes, call me Elodide Bird"

"For these purposes? So that's not your real name then?"

I hated where this talk was going

"No"

"Ohhh, feisty. So what is your real name then?"

"What's yours then?"

"Sebastian. Sebastian Mor.. Verlac. Sebastian Verlac. What's yours then Elodide?"

I rolled my eyes a shouted

"My name if you must know is Elodide Herondale. Now, what do you want?"

**Sebastian**

Her words echoed in my mind

_Herondale. Herondale. Herondale._

But no other Herondales are alive! Are they?

Now I understood who she reminded me of. She was Jace in girl form, with humour and wit lying over something stronger, darker.

I owed it to her to let her meet her brother, or relation.

But she had to be a Nephilim with no connections. It was obvious she had zero connections but on whether she was a shadowhunter or not….

There was only one way to find out.

I took out my stele and she started laughing

"A glass rod? Wow. I though boys carried a phone or money but noooo. I get the weirdo who carries glass in his pockets. Man I know how to pick 'em." She said, with a slight British accent whilst laughing her head off. She was crying with laughter and was doubled up, clutching on to her violin case.

I grabbed her arm and drew two runes. Sleep on her arm and sight on the back of her hand. Her grin rapidly faded.

"Tattooing me? Really?"

She didn't say anymore except swear words as her eyelids started fading. Then I smiled.

"Sleep well Elo"


	5. Chapter 4-Dreams and Revelations

**Elodide**

_I was standing in a large cave, with 2 boys fighting. One of them, had golden wings, the other pure black crescents. Their swords were glowing with a faintish light. They were stained with black and gold liquid, which bore the resemblance to blood. When the one with the black wings turned around, I was stunned. Sebastian. I screamed at them to stop, but there was no end to the carnage. Blood everywhere. Blood, blood, blood_

_More images came to my mind, like shattered glass. A city of glass towers, fighting against demons around the border, Sebastian at its head; a cup, dripping sludgy black blood; an angel, blowing apart the cosmos; a boy with gold hair, holding hands with a red head gesturing me to come with him; a man like Sebastian and an old professor lifting me out of a body. And older scenes. A silver haired boy, playing my violin, evidently Jem Carstairs. Holy water and blood in Victorian London._

I screamed as I woke up. I looked around. I was in a large modern bedroom, with glass everywhere. The walls were black and the wardrobe was open, spilling out women's clothes. Sebastian must be going mad. I felt a cool cloth being placed on my forehead as I smiled.

"Hey there" it was a boys voice with an American accent. "I thought you wouldn't survive. Sorry about Sebastian, but subtlety is not his forte. It's not mine either, but I'm better. Me, sexy hot stuff!"

I was laughing as I looked straight up. There was a boy around my age that had blonde hair and golden eyes. I immediately stopped laughing. Not because of his humour, that was similar to mine or his odd, eyes, like pools of gold or suns. No, none of that. One thing was freaking me out more than anything in my life.

He was the boy fighting Sebastian in my dream. The one extending his hand to me.

I looked up warily and laughed, even though it was forced.

"Ahh! Stranger danger! Just kidding! So 3 things. One, where am I? Two, who are you? And three, could you pass me my violin case? Please…"

"Ohh the girl is demanding things already. Wow how time flies when a girl is demanding"

I rolled my eyes as he went to the wardrobe and pulled out a familiar case. I only wanted to make sure it was safe. I also needed protection and I knew for a fact I had knife in there.

He passed it to me and stated drawing on himself with one of those glass rods that Sebastian drew on me with. Once I had lifted the violin out I started looking at the rod and the spaces for tubes. Then it clicked. I grabbed the rod out of his hand and put it in my case. It fit like a glove.

His eyes widened and he was muttering something that sounded like, 'by the angel!' That must be the same as a swear word.

"I've got to tell Sebastian"

When I was about to say don't he shouted:

"Sebastian! JOHNATHON CHRISTOPHER MORGERNSTERN! GET YOUR BUTT DOWN HERE NOW! SHE IS AWAKE!"

No sooner had he said that someone came rushing in the door. I wanted to punch him. Sebastian.

So I went for the second best thing. My knife in my violin case. I pushed Blondie out of the way and chucked my knife. But I never hit its mark. With shocking speed, Sebastian caught it, right before it hit his head.

"Now, now." He chided "Have some respect. Clothes in the wardrobe, bathroom, second door on your left. We will be in the dining room. "

They left the room and I ran for the bathroom. I hadn't had a wash in years. But I didn't expect in to be in a house with a psychopath and a creepy guy from dreams of death.

Once I had finished, I looked in the wardrobe. Dresses upon dresses, but no jeans or T-shirts. We needed to go shopping. Maybe Sebastian was a drag queen by night. The only thing remotely like jeans was leather pants, leather top and leather combat boots. I quickly pulled them on and was heading out when something stopped me in my tracks.

My reflection.

I didn't have my greasy hair, my hair was gold strands, brushing my waist. The black brought out the gold in my eyes, and the angular panes in my cheekbones. But I was freaking out about the tattoo that Sebastian put on me. One had faded but the eye on my right hand was stark black against my tanned skin. I looked at the other hand, which was unchanged. The pale white star was always as it has been. At least something's didn't change. I was going to kill Sebastian.

I walked down into the dining room, where a mug of tea was on the table, next to Sebastian, whilst Blondie was making lunch.

"El! Sit down! Have some tea."

I gave him a death stare whilst I put my hands around the mug. He seemed to smirk at the star on my left hand.

"Can I help you with something? Apart from bad attitude, of course".

Blondie was laughing his head off. That reminded me, I couldn't keep calling him Blondie forever.

"What's your names? Because I don't know yours, and 'Sebastian' is most likely an alias"

"Your right of course."

"Shocker. No wonder I don't trust you with a 10 foot barge pole."

"Johnathon. Johnathon Christopher Morgenstern"

Blondie smiled

"Jace lightwood"

"Elodide Bird"

Sebastian was amused

"Come on we know they are not your real last names!"

"Say it together?" I asked

"Sure." He replied " 3, 2, 1…."

We shouted together "Herondale!"


	6. Chapter 5-Paper Precipice

Right, ok, A/N. I am so so SORRY people! I have had this project to do and I haven't finished it and it counts towards exams and setting next year! I still haven't finished it but I decided to make you guys a new chapter! COHF in 2 days! (Since I am in the UK)

Sorry I also left you on a cliffhanger (not!)

Also thanks to my readers, reviewers, favoriters (is that a word?) and followers! Also anyone I PM!

You guys are awesome! Whoo!

Also I have a poll on my profile. I would love you if you took part!

DISCLAMER: I don't own tmi. All I own is my OC's and the plot yada yada yah

-lem

**Jace**

"What? We both said together

I felt all the colour drain from my face and I felt like I was falling. Falling into an unknown precipice of shock and doubt. Elodide was clutching the table as her mug fell to the floor, the liquid seeping across the tiles. A crack was heard as the mug broke, shards littering the floor and mixing in with the tea.

But no-one made a move to clean it up.

Sebastian was smirking but concerned as he looked from me to El. She clenched the table with her left hand, the star shape clearly visible.

He said softly to Elodide "do you remember anything about your life before? Anyone like us? Anything may help even if it was in a dream."

"Even in a dream?" she muttered

"Spill" I said, my voice so cold it shocked me.

El just gave me a look of pure death. If looks could kill, I think I may have one of those knives embedded in my chest, her brown eyes like concentrated poison. But under that she was scared of what the truth may be.

"Paper" she said, her voice rising into a half shout, her accent becoming thicker by the minute.

"What?" Sebastian muttered

"And a pencil!" Sebastian sighed as he walked out into the small library.

Whilst he was gone, I and El were just staring at each other wondering if we were related. It couldn't be true.

But the evidence was staring me in the face. Same hair, only hers was impossibly long, almost reaching her waist. Same features, same glint in her eye that told me that she was the master of sarcasm and insults. She couldn't be as good as me though. The only thing that was different was her eyes. Whilst mine were gold, hers were a brown colour with gold in. Must be from Celine. Our biological mother. But like me, she never classed her as her mother. She didn't have a mother whilst mine was Maryse.

Whilst I was thinking about this Sebastian walked in a chucked some paper on the table.

"So what is it you want to show us?" I said.

But she was away. I recognised the concentration on her face as I came up behind El and looked over her shoulder.

You could have heard a pin drop. The scratching of the pencil made me look down.

She was good. I admit that. She had captured 2 shadowhunters perfectly, in the midst of trying to grab something on our side of the paper. I was literally like someone had took a photo.

She chucked the pencil towards Sebastian, as he was engrossed in some papers, the pencil just going to the right of his ear, nicking off a bit of skin. From her expression, she meant to do that.

"Finished sweetheart? He said, his voice dripping in malice.

She looked unaffected as he looked down at the paper. He looked shocked. It was the first time he had saw emotion from him since….

The memory was wiped from my mind as soon as it came.

Sebastian was staring down at the paper, looking like he wanted to burn it.

I looked again, I now recognised the shadowhunters.

Hodge.

And Valentine.

"How?" I said in a whisper towards El

"Oh! Photographic memory a shed load of talent if I don't say so myself, pencils, paper…"

"No. how did you see this?"

"In a dream, but I think it was a memory. Who is it?"

Sebastian muttered "our father, well my biological father, Jace's adopted one and Jace's tutor"

"What happened to them?"

"Dead"

Rage surged within me. Valentine. That evil so called person. At least he got justice and was in hell now.

"This all adds up." Sebastian said, his eyes glazed.

"What?"

"The star on the hand, the personality, the features"

"Hey I am still here!"

He continued "the backstory and the notes…"

"What notes?" I asked

He slammed the papers down on the table, hiding Valentines face from view. He then began to read

"_The children are doing well, but Stephens's girl is weak. Whilst her brother progresses, she does not. She never has. I cannot kill a child, so I must send her away to an orphanage. A mundane one. It disgusts me but I have no choice. I will collect her when the time is right."_

"Weak?!" she muttered. "Why the little…." The she started saying a few words that Valentine would not approve of.

"See?" Sebastian said "it all fits"

"No" I muttered, fear of the truth gnawing inside me. I was not falling into a precipice any more, but a paper precipice, filled with notes of Valentine.

"Yes Jace. She is your Sister."

**Sebastian**

I could not believe I was saying those words.

But then again, it all fit. She was Jace in girl from, but less annoying and cuter, obviously.

Wait what was I saying? To love is to destroy. But Jace forgot that and he got Clary.

Clary…

I saw Jace hug Elodide, looking like the air was coming out of her. I was not surprised when she started hitting him, forcing her to let go

"Aww my ickle sister has some bite!"

"Shut it. So what do we do now?" she turned towards me as she said these. She looked so confident, radiant. I liked that. Seeing her gear made me decide.

"We train"

She unclenched the table as she walked off Jace just in front of her. I noticed a handprint scored into the table as I walked off, the smell of burning following me.


	7. Chapter 6-Gold and Platinum

A/N: ok I am sorry again but exams are coming up behind me with vengeance.

Thanks to all of the fans of this story! You have skills!

Also many thanks to Riiver. Major skills my fangirling buddy! Check out her stories!

10 points for anyone who spotted my weird divergent reference!

I don't own TMI. Otherwise I would be doing a happy dance!

-lem

**Elodide**

We slowly make our way down the stairs with my annoying sibling and Sebastard. What? It's a good name for him.

"Sooo…. Who are you guys? Vigilante killers? If so, I want in."

"Noooo…." He said mimicking my accent. I scowled as he continued, shaking his golden curls. "We are Shadowhunters"

"Thank you for that helpful explanation, brother". The word still felt alien on my tongue

Sebastian smirked. "You know about angels and demons right?"

"Yeah soo…." Then it hit me. Michael once told me an old story about a race of people who killed demons for a living, and had their own magic. You had to be born into it, or be transformed by a... cup I think? No way. No fudging way.

"Christ" I said "Are the stories true?"

"All the stories are true. That's the unofficial motto" Sebastian said

"Well not correct. The unofficial motto is Jace Lightwood. Looking better in black than you ever will."

"That's your unofficial motto" I laughed, doubling up and clutching the railings. But then I remembered the table and I stopped immediately. Hopefully no one would notice the burn mark in the table. Yeah, that's going to happen.

We walked into a short corridor, with 2 doors on it. One was open but the other was locked, protected by symbols that I didn't know. But, the spoke of something dark, of capture and imprisonment.

"What's behind that?

"Nothing. Nothing" Sebastian replied, a little nervously. Ok, some something was behind that door. Note to self: find out about that later.

We walked into the other door. My jaw fell open as I looked around.

Row upon row of weapons glistened back at me. Knives, those weird glass rods, longer ones, hammers, and….. Was that an axe?

"Ok then" Sebastian went all business like. "This is a seraph blade" he pointed to one of the long rods hanging up. Then he grabbed it and gave it to me. "Say a name of an angel and boom!"

"Boom?"

"Just try"

"Bob! Dave! Larry!" Jace sniggered in the background.

"Michael" I whispered, grief shooting though me, even though he wasn't dead, just gone.

It automatically lit up and a sharp blade sprung from it. It was too long to be classed as a dagger, but too short to be a sword.

"Oh" I said.

"Oh?" Jace repeated. Is that all you can say?

"What do you expect me to do? A song and dance?"

Sebastian grabbed it back.

"This is a knife" he explained, pointing to it on the wall.

I started mock clapping. "Wow! Do you think if I know what an axe is a may progress?"

Jace was laughing in the corner and Sebastian just rolled his eyes. Obviously no sense of humour was available at this moment in time. Leave a message after the screams.

"Obviously related. Sarcasm must run in the family"

"What runs in yours then, Sebastian?"

He went like a block of stone then. Whoa. Touchy subject. Ask Jace later.

"Ok then, since you are so clever, let's fight"

"Sebastian I don't think..."

His eyes then glazed over as he said "Fine Morgenstern"

No no no no no! Morgernstern? That was my song about love. Ironic, that I can't stand Sebastian. Then something else came into my mind. My brother wouldn't stay with Sebastian of his own accord.

He was forced to.

Sebastian was looking at me with hate. "Pick a weapon" he said whilst drawing a sword from his belt, the stars stamped on the blade shining. Morgernstern. Stern. Star. Ohh. I picked up a sword about the length of my arm, maybe longer.

"Fight." Jace said, a board expression on his face.

I went to swing my sword but he was gone. I looked around in confusion. Then I looked up. He was perched crookedly on the rafters, the wooden beams groaning under his weight. "Jump. Or are you too scared"

_Jump. Be anything Elodide Theresa Herondale. Even as light as a feather. Be anything. _My subconscious sounded creepily like Michael. Michael was never wrong.

So I jumped.

I landed next to Sebastian, with him smirking. I ducked right before the sword cleaved my head in 2. "Scared Herondale?" he said as I parried his next stroke.

"I could knock seven bells out of you any day"

He looked confused. I took the opportunity to slam the butt of my sword into the small of his back.

He fell from the rafters, looking like Lucifer as he was falling. I jumped aiming right next to him. A good clean land was all I needed. But that never happened. I jumped, but I lost my grip on the sword and tumbled down, landing straight on his chest.

I looked down. His dark eyes were full of emotion, like a war was raging inside of him. But then I thought I saw a flash of green in them before they changed to the dark pools that I knew. The scent of black pepper and lemon filled my nostrils. Gold mixing with platinum. He made no move to get up and neither did I. I felt a hand pull me up. Jace. Wow, way to ruin the romantic moment.

Wait, romantic? I hated Sebastian. Snarky to good for nothing, argh!

"Where did you get that?" he muttered, ice crystallising off of him. I looked down at my tattoo of the eye. I pointed toward the one and only Sebastian. Then he went into what I could only describe as older brother mode, even though we were twins.

"JOHNATHAN CHRISTOPHER MORGERNSTERN! WHAT ON EARTH WERE YOU THINKING! YOU COULD HAVE TURNED HER INTO A GODDAMN FORSAKEN!"

"But I didn't! We better give her the marks because of the task."

"Fine he said, stalking out of the room like a 7 year old in a tantrum. Sebastian and I shared a single look before following him out of the door, past the mysterious room. I thought I heard a single scream before we went up the stairs.

I needed to find out what was behind that door.


End file.
